Matt, Barry, Should I do any particular trick to solve block matrices in ksp?
I am doing a silly 3x3 cavity test case and I am struggling to converge using CG+bjacobi. It might be I have an error in the matrix, but just to be sure I am not missing something fundamental in the setup. This is my log that shows how norm residual is far to be happy: *10000 *KSP unpreconditioned resid norm 2.273088479279e+03 true resid norm 2.273088479279e+03 ||r(i)||/||b|| 6.561841227018e+02 Reason = -3 ERROR: KSP has not converged. Simulations stopped. [0]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- [0]PETSC ERROR: KSPSolve has not converged, reason DIVERGED_ITS Thank you